diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4b8a7f3..d57cd86 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,9 @@
 # Changelog
 
-## Unreleased
+## Version 4.12.1, 9/1/2026
+
+The first PyPI release: `pip install mercury-composable`. The v4.12.0 lock-step line
+plus the AI-node demo functions below.
 
 ### Added
 
@@ -18,6 +21,9 @@
   progressively out its own HTTP edge as SSE. Terminal metadata carries model,
   stop_reason, usage and the trace/business correlation ids; provider errors fail the
   stream in-band. Live-proven end to end with real Gemini tokens (2026-08-31).
+- PyPI publication metadata: SPDX license expression (PEP 639), trove classifiers,
+  keywords, project URLs, and a constrained sdist (package sources, tests, examples
+  and top-level docs only - repo-internal layers never ship).
 
 ## 4.12.0 (2026-08-30)
 
diff --git a/pyproject.toml b/pyproject.toml
index e5fbcd3..20d4512 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,10 +4,11 @@ build-backend = "hatchling.build"
 
 [project]
 name = "mercury-composable"
-version = "4.12.0"
+version = "4.12.1"
 description = "Lightweight Event-over-HTTP function host and client for Mercury Composable"
 readme = "README.md"
-license = { file = "LICENSE.txt" }
+license = "Apache-2.0"
+license-files = ["LICENSE.txt"]
 authors = [{ name = "Accenture Technology" }]
 requires-python = ">=3.10"
 dependencies = [
@@ -15,16 +16,26 @@ dependencies = [
     "msgpack>=1.0,<2",
     "PyYAML>=6.0,<7",
 ]
+keywords = ["event-driven", "composable", "microservices", "event-over-http", "mercury"]
 classifiers = [
-    "Development Status :: 3 - Alpha",
-    "License :: OSI Approved :: Apache Software License",
+    "Development Status :: 4 - Beta",
+    "Intended Audience :: Developers",
     "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: 3.13",
+    "Programming Language :: Python :: 3.14",
     "Framework :: AsyncIO",
+    "Topic :: Software Development :: Libraries",
+    "Operating System :: OS Independent",
 ]
 
 [project.urls]
 Homepage = "https://github.com/Accenture/mercury-python"
-Documentation = "https://accenture.github.io/mercury-composable"
+Documentation = "https://accenture.github.io/mercury-python"
+Repository = "https://github.com/Accenture/mercury-python"
+Changelog = "https://github.com/Accenture/mercury-python/blob/main/CHANGELOG.md"
 
 [project.optional-dependencies]
 # the llm.chat demo function (examples/demo_app.py) - the package itself stays SDK-free
@@ -37,6 +48,18 @@ mercury-serve = "mercury_composable.cli:main"
 [tool.hatch.build.targets.wheel]
 packages = ["src/mercury_composable"]
 
+[tool.hatch.build.targets.sdist]
+# the sdist ships the package plus its teaching surfaces - never the repo's
+# agent-memory layer, skills, or CI plumbing
+only-include = [
+    "src/mercury_composable",
+    "tests",
+    "examples",
+    "README.md",
+    "CHANGELOG.md",
+    "LICENSE.txt",
+]
+
 [tool.ruff]
 line-length = 100
 target-version = "py310"
diff --git a/src/mercury_composable/version.py b/src/mercury_composable/version.py
index 2956cc5..077a3cb 100644
--- a/src/mercury_composable/version.py
+++ b/src/mercury_composable/version.py
@@ -1,3 +1,3 @@
 """Package version - the single Python-side source (pyproject.toml mirrors it)."""
 
-__version__ = "4.12.0"
+__version__ = "4.12.1"